Mobile networks such as 2G, 3G and 4G, and local area networks such as WLAN and WIFI are currently common techniques providing internet access for network terminal devices. Generally, network terminal devices, especially mobile internet devices such as mobile phones, notebook computer, and network access facilities on a moving vehicle, are provided with both mobile network and local area network access functions. A user can switch between different networks as needed, often manually. Networks' charges vary with mobile network significantly expensive than local area network. Therefore, network devices generally select local area networks as default when both networks are available and switch to a mobile network automatically when local area network is not available, in order to minimize costs. In this scenario, if a user needs to switch from a local area network to a mobile network when for example the signal of the local area network is too weak to use, the user has to disable the local area network access function. This is because the default setting of the network devices always enables it to switch into a local area network wherever a local area network is available.
The automatic switching setting built in current network devices, however, damages some of user experiences, although access fees are largely reduced. For example, a user definitely does not wish the media streams that are being played on the device, such as videos or audios, to be disrupted. However, due to current default settings in the network device, even when the local area network is so weak that it is not able to provide smooth playing, the device will not switch automatically to a faster mobile network. This often results in intermittent playing of the videos or audios, which negatively influences the joy of the user.
In this scenario, the network device will not switch into a mobile network until the signal of the local area network disappeared. Local area network signals are not evenly distributed, for example, when the network device is installed on a vehicle, or the signals are subject to wall separation, or a plurality of signals with various strengths coexists in same area. The uneven distribution causes the frequent switches between local area network and mobile network, which enhances power consumption and heat generation, despite of the fact that the expenses of mobile network access is reduced due to full use of local area networks.
The internet access through a local area network hinges on connection to a local area network device, such as a WIFI router, and then through the local area network device to a wide area network. However, the network device is not able to determine, by itself, whether the local area network device is connected to the wide area network. The network device will not be able to connect to the wide area network when the local area network is disconnected with the wide area network, although in this case it is shown that the network device is successfully connected to the local area network and even with a strong signal. Under the current default setting, the network device connects to the local area network all the time and does not automatically switch to a mobile network.